How do I generate a controller spec using rspec?

If you are using Rails 3 + rspec and you installed rspec (rails g rspec:install), it should generate controller specs for each controller you generate (and others objects).

If you need to create one by hand. Just create a new new_controller_name_spec.rb in your spec/controllers.

require 'rails_helper'

describe NewControllerName do
  # Test!
end

You could also try to re-generate the controller file, say No when it asks you if you want to overwrite the existing controller, and hopefully it will regenerate the rspec for that controller again.

the rspec way is

rails g rspec:controller passwords

it gives

create  spec/controllers/passwords_controller_spec.rb

--Update

You can configure your application to generate rspec when model or controller is created. Add to config/application.rb

# don't generate RSpec tests for views and helpers.
config.generators do |g|
  g.test_framework :rspec, fixture: true
  g.fixture_replacement :factory_girl, dir: 'spec/factories' 

  g.view_specs false
  g.helper_specs false
end

$rails g model category
  invoke  mongoid
  create    app/models/category.rb
  invoke    rspec
  create      spec/models/category_spec.rb
  invoke      factory_girl
  create        spec/factories/categories.rb
$rails g controller categories
  create  app/controllers/categories_controller.rb
  invoke  haml
  create    app/views/categories
  invoke  rspec
  create    spec/controllers/categories_controller_spec.rb
  invoke  helper
  create    app/helpers/categories_helper.rb
  invoke    rspec
  invoke  assets
  invoke    coffee
  create      app/assets/javascripts/categories.js.coffee
  invoke    scss
  create      app/assets/stylesheets/categories.css.scss

As of Rails 5 and RSpec 3.5, controller spec files are no longer the recommended approach, instead RSpec creates files called requests. These files test the output of your controllers by testing what happens when a request is made to a given URL.

Consider the following:

rails g rspec:controller fruits

Pre-Rails 5 you would get a file like:

spec/controllers/fruits_controller_spec.rb

With Rails 5 you would get a file like:

spec/requests/fruits_request_spec.rb

The RSpec 3.5 release notes have more to say on this:

The official recommendation of the Rails team and the RSpec core team is to write request specs instead. Request specs allow you to focus on a single controller action, but unlike controller tests involve the router, the middleware stack, and both rack requests and responses. This adds realism to the test that you are writing, and helps avoid many of the issues that are common in controller specs.

Hope this helps anyone who stops by because they were trying to figure out why Rails wasn't making controller specs!